Carrier Assembly for a Selective Catalytic Reduction System and a Selective Catalytic Reduction System

ABSTRACT

A carrier assembly for a selective catalytic reduction system includes a heater, at least one wire heater, a first holding element, and a second holding element. The heater is configured to heat a working medium from a tank. A first end of the wire heater is connected to the first holding element and a second end of the wire heater is connected to the second holding element. Such a carrier can be included in a supply module and a selective catalytic reduction system.

This application claims priority under 35 U.S.C. § 119 to patent application number IN 201741007165 filed on Mar. 1, 2017 in India, the disclosure of which is incorporated herein by reference in its entirety.

The disclosure relates to a carrier assembly for a selective catalytic reduction system.

BACKGROUND

Selective Catalytic Reduction system is a technology used in diesel engines to reduce NOx emissions by utilizing a chemical reaction between aqueous urea solution and exhaust gas. The hydraulic circuit of selective catalytic reduction system consists of a storage tank, a pump, filters, valves, a hose and a spraying device and aqueous urea solution as working medium. In general, the supply module pumps the working medium to the dosing module. Before pumping the working medium, the working medium is filtered so as to ensure that clean working medium is supplied to the dosing module. The main filter is permanently fixed or welded with the carrier assembly, which holds the level sensor. The carrier assembly is fitted to the tank. At subzero temperature conditions, the working medium freezes and so a heater is required to heat the working medium and to ensure working medium supply to the supply module.

The U.S. Pat. No. 8,479,497B2, explains the method of operating an SCR converter.

SUMMARY

The disclosure provides for a method for operating an SCR catalytic converter for the after treatment of exhaust gases of an internal combustion engine, wherein a reducing agent tank with reducing agent and a reducing agent metering device are provided. The reducing agent tank has at least one tank heater having PTC characteristics. A variable characterizing the heater current is acquired for detecting cavities in the reducing agent tank when the reducing agent is frozen. The presence of cavities is suggested from a deviation of the acquired value or values for the variable characterizing the heater current from a pre determinable reference value, which represents a reducing agent tank without cavities.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the disclosure are explained in principle below with reference to the drawings. The drawings are:

FIG. 1 illustrates a view of a selective catalytic reduction system 100 according to an embodiment of the disclosure;

FIG. 2 illustrates a view of a carrier assembly 200 with a cavity 301 according to an embodiment of the disclosure; and

FIG. 3 illustrates another view of a carrier assembly 200 according to another embodiment of the disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a carrier assembly 200 for a selective catalytic reduction system 100. The carrier assembly 200 comprises a heater 201 and the heater 201 is adapted to heat a working medium in a tank 300. The carrier assembly 200 further comprises at least one wire heater 202 having two ends 202 a, 202 b. A first end of the two ends 202 a, 202 b of the wire heater 202 is adapted to receive power from a bus bar in the carrier assembly 200 and a second end of the two ends 202 a, 202 b of the wire heater 202 is connected to a holding element 203.

According to an embodiment of the disclosure, the holding element 203 is a floating element. For example the holding element 203 is a ball element which floats on the surface of the working medium when the tank 300 is filled. One end of the two ends 202 a, 202 b of the wire heater 202 is connected to the holding element 203 and the other end of the two ends 202 a, 202 b of the wire heater 202 is connected to the bus bar of the carrier assembly 200 to get the power for the wire heater 202 to operate.

According to an embodiment of the disclosure, the holding element 203 is a spring element. The spring element is connected to a top of the tank 300 from one end and the wire heater 202 on the other end. So the wire heater 202 is hung from the spring element from one end and from other end, the spring element is connected to the top or the roof of the tank 300.

According to an embodiment of the disclosure, the at least one wire heater 202 comprises at least one wire connected to the holding element 203 from one end. The wire heater 202 comprises of at least one wire which is connected to the holding element 203 on one end and to the bus bar of the carrier assembly 200 on the second end. In one case as shown in FIG. 3, the wire heater 202 can have multiple wire heater 302 a whose one end is connected to the one holding element 203 a and the second end is connected to one bus bar of the carrier assembly 200 to receive power.

The supply module 400 for a selective catalytic reduction system 100 comprises a pump 401 fitted to a carrier assembly 200 and the carrier assembly 200 comprising a heater 201. The heater 201 is adapted to heat a working medium from a tank 300. In the supply module 400, the carrier assembly 200 further comprises at least one wire heater 202 having two ends 202 a, 202 b. The first end of the two ends 202 a, 202 b of the wire heater 202 is adapted to receive power from a bus bar in the carrier assembly 200 and the second end of the two ends 202 a, 202 b of the wire heater 202 is connected to a holding element 203.

The set-up of wire heater 202 in the tank 300 is always in such a way that one end of the two ends 202 a, 202 b of the wire heater 202 is connected to the holding element 203 and the other end of the two ends 202 a, 202 b of the wire heater 202 is connected to the bus bar of the carrier assembly 200 to receive the power.

The selective catalytic reduction system 100 comprises a tank 300 for a working medium, a supply module 400, a carrier assembly 200 and a dosing module 500. The tank 300 has an inlet port for receiving the working medium inside the tank 300. The supply module 400 is fitted in the tank 300. The supply module 400 comprises a carrier assembly 200 and a pump 401 fitted to the carrier assembly 200. The carrier assembly 200 comprises a heater 201. The heater 201 is adapted to heat the working medium from a tank 300 and the dosing module 500 is adapted to receive the working medium from the supply module 400. The carrier assembly 200 comprises at least one wire heater 202 having two ends 202 a, 202 b, the first end of the two ends 202 a, 202 b of wire heater 202 is adapted to receive power from a bus bar of a carrier assembly 200 and second end of the two ends 202 a, 202 b of the wire heater connected to a holding element 203.

The main aim of this disclosure disclosed above is to refill the working medium in the tank at negative temperature or subzero temperatures when there is no working medium left for thawing process and the working medium present in the tank 300 is in frozen state. With reference to FIGS. 1, 2 & 3, at negative temperature conditions, when the working medium 303 is frozen, the main heater 201 is activated. The main heater 201 melts the frozen working medium 303 and this process is known as thawing process. The main heater 201 can thaw a limited volume of the working medium 303 during short driving cycles and the melted working medium is extracted by supply module 400 and sprayed to the dosing module 500. Generally in the tank 300, there is always a space left while filling the working medium. When the climatic temperature goes down for example below −7 degree centigrade then the working medium 303 tends to freeze and as the working medium 303 freezes it expands in volume. For accommodating the frozen working medium 303, the space is left in the tank 300. The main heater 201 on the carrier assembly 200 is used to defrost the frozen working medium 303. Since the position of the main heater 201 is fixed, thawing capability of heater 201 is not sufficient to thaw the whole frozen working medium 303 of the tank 300 at negative temperature conditions. Once the defrosted working medium is pumped out into an exhaust pipe, it forms a cavity 301 and refilling is not possible because the working medium 303 cannot reach the cavity 301 due to the frozen working medium 303 surrounding the cavity 301. With the wire heater 202, once the cavity 301 is formed, the wire heater 202 is activated and it starts melting the working medium around the wire heater 202.

Due to gravitational force, the melted working medium 303 flows down towards the cavity 301 and form a passage 302 from the holding element 203 to the cavity 301. The working medium 303 now can be refilled, as while refilling the working medium 303 will flow through the passage 302 around the wire heater 202 and reach the cavity 301. Once the cavity 301 is filled the selective catalytic reduction system 100 is again ready for use.

It must be understood that the embodiments explained in the above detailed description in only illustrative and does not limit the scope of this disclosure. The scope of this disclosure is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this disclosure. 

1. A carrier assembly for a selective catalytic reduction system, comprising: a heater configured to heat a working medium from a tank; a first holding element; and at least one wire heater including: a first end configured to receive power from a bus bar in the carrier assembly; and a second end connected to the holding element.
 2. The carrier assembly as claimed in claim 1, wherein the first holding element is a floating element.
 3. The carrier assembly as claimed in claim 1, wherein the first holding element is a spring element.
 4. The carrier assembly as claimed in claim 1, wherein the at least one wire heater further includes at least one wire with a third end connected to the first holding element.
 5. A supply module for a selective catalytic reduction system, comprising: a carrier assembly including: a heater configured to heat a working medium from a tank; a first holding element; and at least one wire heater including: a first end configured to receive power from a bus bar in the carrier assembly; and a second end connected to the holding element; and a pump fitted to the carrier assembly.
 6. A selective catalytic reduction system comprising: a tank for a working medium, the tank including an inlet port that enables working medium to enter the tank; a supply module positioned in the tank, the supply module including: a carrier assembly having: a heater configured to heat the working medium from the tank; a first holding element; and at least one wire heater with: a first end configured to receive power from a bus bar in the carrier assembly; and a second end connected to the holding element; and a pump fitted on the carrier assembly; and a dosing module configured to receive the working medium from the supply module. 